517 


UC-NRLF 


SB    3M 


EXCHANGE 


The  Dissociation  of  Electrolytes  in 
Nonaqueous  Solvents  as  Deter- 
mined by  the  Conductivity  and 
Boiling-Point  Methods 


DISSERTATION 


SUBMITTED  TO  THE  BOARD  OF  UNIVERSITY  STUDIES  OF 

THE  JOHNS  HOPKINS  UNIVERSITY  IN  CONFORMITY 

WITH  THE  REQUIREMENTS  FOR  THE  DEGREE 

OF  DOCTOR  OF  PHILOSOPHY 


BY 


HENRY  ROYER  KREIDER 


June,  1910 


EASTON,  PA. 

ESCHENBACH  PRINTING  COMPANY 
1911 


The  Dissociation  of  Electrolytes  in 
Nonaqueous  Solvents  as  Deter- 
mined by  the  Conductivity  and 
Boiling-Point  Methods 


DISSERTATION 


^  U3MITTED  TO  THE  BOARD  OF  UNIVERSITY  STUDIES  OF 

THE  JOHNS  HOPKINS  UNIVERSITY  IN  CONFORMITY 

WITH  THE  REQUIREMENTS  FOR  THE  DEGREE 

OF  DOCTOR  OF  PHILOSOPHY 


BY 


HENRY  ROYER  KREJDER 


EASTON,  PA. 

ESCHENBACH  PRINTING  COMPANY 
1911 


1JLZ170 


CONTENTS 


Acknowledgment 4 

Introduction 5 

PART  I 
HISTORIC  AL  REVIEW: 

Nonaqueous  Solvents 5 

Mixed  Solvents 6 

PART  II 
EXPERIMENTAL  : 

Apparatus 17 

Salts 19 

Solvents 20 

Solutions 20 

EXPERIMENTAL  DATA: 

Conductivity  in  Pure  Solvents 21 

Conductivity  in  Mixed  Solvents 25 

Boiling  Point 31 

THEORETICAL: 

Discussion  of  Results 32 

Conductivity  in  Pure  Solvents 32 

Conductivity  in  Mixed  Solvents 33 

Ratios  of  Conductivity  between  Different  Alcohols 43 

Boiling  Point  Data 45 

Summary 46 

Biography 48 


222270 


ACKNOWLEDGMENT 

The  author  takes  great  pleasure  in  expressing  a  deep  sense 
of  appreciation  and  gratitude  to  President  Remsen,  Professor 
Morse  and  Professor  Jones  for  instruction  and  advice  which 
were  at  all  times  generously  given  both  in  the  laboratory  and 
in  the  lecture  room. 

He  also  desires  to  thank  Professor  Renouf ,  Associate  Pro- 
fessor Acree,  Doctor  Gilpin  and  Associate  Professor  Swartz. 

This  investigation  was  undertaken  at  the  suggestion  of  Pro- 
fessor Jones  and  pursued  under  his  direction. 


The  Dissociation  of  Electrolytes  in  Nonaqtieous 

Solvents  as  Determined  by  the  Conductivity 

and  Boiling-point  Methods 


Four  methods  have  been  devised  for  measuring  the  disso- 
ciation of  salts  in  solution:  The  conductivity  and  freezing- 
point  methods,  the  solubility  method  of  Nernst  and  Noyes, 
and  the  boiling-point  method.  Of  these  the  conductivity  and 
freezing-point  methods  are  the  best  known,  and  are  the  most 
accurate.  The  solubility  method  of  Nernst  and  Noyes  is  not 
widely  applicable.  Within  recent  years  the  boiling-point 
method  has  been  so  much  improved  by  Jones  and  others  that 
it  gives  fairly  accurate  results. 

There  are  certain  objections  to  all  of  these  methods.  The 
conductivity  and  the  freezing-point  methods  give  good  results 
in  aqueous  solutions,  but  in  nonaqueous  solutions  which  are 
less  dissociated,  their  use  has  been  attended  with  difficulty. 
In  many  of  these  solvents  it  has  not  been  possible,  previous  to 
the  present  time,  to  determine  /i^  accurately,  and,  conse- 
quently, the  dissociation  could  not  be  calculated  from  the 
results  obtained  by  the  conductivity  method.  Many  of  the 
nonaqueous  solvents  freeze  at  a  temperature  so  far  below  the 
ordinary  that  the  application  of  the  freezing-point  method  is 
often  impossible. 

By  means  of  the  latest  type  of  cell  devised  in  this  labora- 
tory, and  which  will  be  described  later,  we  have  been  able  to 
measure  /t^  for  a  number  of  salts  in  methyl  and  ethyl  alco- 
hols, and  thus  to  calculate  the  dissociation  of  these  salts  in 
these  solvents  from  the  data  obtained  by  the  conductivity 
method.  The  dissociation  of  these  same  salts  in  the  same 
solvents  was  determined  by  the  boiling-point  method  with  the 
object  of  finding  if  any  relation  exists  between  the  results 
obtained  by  the  two  methods. 

HISTORICAL   REVIEW. 

A  large  amount  of  work  has  been  done  with  nonaqueous 


solvents,  especially  with  the  lower  alcohols  of  the  aliphatic 
series.  These  were  soon  found  to  have  the  property  of  dis- 
sociating salts  to  a  considerable  extent.  Fitzpatrick1  studied 
the  conductivities  of  calcium  nitrate,  lithium  nitrate,  lithium 
chloride  and  calcium  chloride  in  both  methyl  and  ethyl  alco- 
hols, and  found  values  which  were  considerable,  though 
less  than  those  in  water.  Hartwig2  measured  the  conductivity 
of  a  number  of  organic  acids  in  both  methyl  and  ethyl  alco- 
hols. Paschow3  worked  with  potassium  iodide,  cadmium 
iodide,  calcium  iodide,  potassium  acetate  and  sodium  acetate 
in  methyl  alcohol.  Vicentini4  measured  the  conductivities 
of  a  number  of  salts  of  these  alcohols.  Cattaneo,5  working 
with  salts  in  ethyl  alcohol,  found  that  a  number  of  those 
with  which  he  worked  have  a  negative  temperature  coefficient 
in  this  solvent.  Vollmer6  studied  several  salts  over  a  large 
range  of  dilutions.  Holland7  investigated  the  effects  of  non- 
electrolytes  on  the  conductivity  of  various  salts  in  methyl  alco- 
hol. Carrara's8  work  is  very  important.  He  carried  out  an 
extensive  investigation  on  a  large  number  of  salts  in  methyl 
alcohol.  Walden9  did  a  large  amount  of  work  with  pure 
organic  solvents.  The  work  of  Dutoit  and  Aston10  and  of 
Frederich11  is  important.  They  formulated  the  hypothesis 
that  the  dissociating  power  of  a  solvent  is  a  direct  function  of  its 
degree  of  association  in  the  pure  state.  Other  workers  in  this 
field  are  Kablukoff,12  Vollmer,13  and  Kahlenberg  and  Lincoln.14 

Mixed  Solvents. 
Wakeman15  carried  out  an  investigation  on  organic  acids  in 

1  Phil.  Mag.,  24,  378  (1893). 

2  Wied.  Ann.,  33,  58  (1888);  43,  838  (1891). 

3  Charcow,  1892. 

*  Beibl..  Wied.  Ann.,  9,  131  (1885). 

5  Ibid.,  18,  219,  365  (1894). 

8  Wied.  Ann.,  52,  328  (1894). 

7  Ibid..  50,  263  (1893). 

»  Gazz.  Chim.  Ital.,  [1]  26,  119  (1896). 

•Z.  physik.  Chem.,  5,  35  (1890). 

10  Compt.  rend.,  125  240  (1897). 

"  Bull.  Soc.  Chim.,  [3]  19,  321  (1897). 

»  Z.  physik.  Chem.,  4,  432  (1889). 

»  Wied.  Ann.,  52,  328  (1894). 

"  J.  Phys.  Chem.,  3,  26  (1899). 

w  Z.  physik.  Chem.,  11,  49  (1893). 


mixtures  of  water  and  ethyl  alcohol  and  found  that  the  con- 
ductivity of  these  substances  in  these  solutions  decreased  with 
increasing  amounts  of  alcohol.  Zelinski  and  Krapiwin1  point 
out  that  the  salts  with  which  they  worked,  the  iodides  and 
bromides  of  sodium  and  ammonium  in  mixtures  of  50  per  cent. 
methyl  alcohol  and  water,  give  a  conductivity  considerably 
less  than  the  conductivity  of  these  salts  in  either  pure  alcohol 
or  water.  Cohen2  gives  similar  results  with  ethyl  alcohol 
and  water,  and  finds  that  potassium  iodide  in  80  per  cent. 
alcohol  shows  a  larger  conductivity  below  V  =  512  than  in 
pure  alcohol,  but  at  a  greater  dilution  the  conductivity  is 
less  in  the  mixed  solvents  than  it  is  in  either  of  the  pure  sol- 
vents. Wakeman,3  working  with  mixtures  of  ethyl  alcohol 
and  water,  found  that  the  equation, 

A 

—7  -     —  r-  =  constant 
p(ioo-p) 

held  for  many  substances  in  mixtures  of  the  above-named 
solvents  (A  is  the  difference  between  the  conductivity  of  the 
electrolyte  in  water  and  in  the  mixture,  and  p  the  percentage 
of  alcohol  by  volume)  . 

From  his  own  and  from  Wakeman  's  observations  Cohen 
points  out  the  following  relation: 


—  constant. 

This  relation  holds  independently  of  temperature  and  con- 
centration. He  remarks  that  either  the  dissociation  of  the  salt 
with  which  he  worked  is  the  same  or  that  in  these  mixtures 
conductivity  is  not  a  direct  measure  of  dissociation.  Roth 
later  found  that  the  relation  given  by  Wakeman  holds,  while 
that  given  by  Cohen  does  not. 

Jones4  and  his  coworkers  have  done  a  fairly  large  amount  of 
work  on  conductivity  and  viscosity  in  mixed  solvents.  Since 
the  following  is  essentially  a  continuation  of  that  work  a  very 
brief  review  of  the  latter  is  necessary. 

1  Z.  physik.  Chem.,  21,  35  (1896). 

?  Ibid.,  25,  31  (1898). 

*Jbid.,  11,49  (1893). 

4  Publication  No.  80,  Carnegie  Institute. 


8 

Jones  and  Lindsay1  found  that  the  phenomenon  discovered 
by  Zelinski  and  Krapiwin  is  not  confined  to  a  few  salts  in 
mixtures  of  methyl  alcohol  and  water  only,  but  that  it  holds 
over  a  large  range  of  salts  and  also  in  ethyl  alcohol- water  mix- 
tures. It  holds  less  generally  at  25°  than  at  o°,  and  in  ethyl 
alcohol-water  mixtures  less  than  in  methyl  alcohol-water  mix- 
tures. The  conductivities  were  always  less  than  the  mean 
calculated  from  the  conductivities  in  the  pure  solvents. 

As  a  partial  explanation  they  advance  the  following  tenta- 
tive suggestion:  According  to  the  theory  of  Dutoit  and  Aston 
only  the  polymerized  molecules  of  the  solvent  dissociate  the 
molecules  of  the  solute.  It  is  well  known  that  water  and  the 
alcohols  used  are  bighly  associated  substances.  On  coming 
into  contact  with  each  other,  they  break  down  the  association 
of  each  other  until  equilibrium  is  reached;  and,  consequently, 
they  have  less  dissociating  power.  In  methyl  alcohol-water 
mixtures  where  association  of  the  constituents  is  greatest  the 
dissociation  is  greatest.  Other  facts  are  in  accordance  with 
this  suggestion.  Since  at  the  lower  temperatures  the  associa- 
tion is  greatest  in  the  constituents,  we  would  expect  the  great- 
est abnormality  here.  And  such  is  the  case. 

These  conclusions  were  subsequently  further  confirmed  by 
the  cryoscopic  work  of  Jones  and  Murray.2  They  worked 
with  water  and  formic  and  acetic  acids,  and  determined  the 
molecular  weights  of  each  in  the  other  by  the  freezing-point 
method.  They  found  that  the  molecular  weights  of  these 
substances  are  always  less  than  the  molecular  weights  of  the 
pure  substances  as  determined  by  the  method  of  Ramsay 
and  Shields.  They  thus  conclude  that  the  action  of  an  as- 
sociated solvent  upon  another  associated  solvent  is  analogous 
to  the  action  of  an  associated  solvent  upon  an  electrolyte. 

Jones  and  Carroll3  extended  the  work  of  Jones  and  Lindsay. 
They  worked  with  both  binary  and  ternary  electrolytes. 
As  solvents  they  used  methyl  and  ethyl  alcohols  and  mixtures 
of  these  two.  Acetic  acid  was  also  used.  In  mixed  solvents 

1  Am.  Chem.  J.,  28,  329  (1902).     Z.  physik.  Chem.,  56,  129  (1906). 

2  Ibid.,  30,  193  (1903). 
«  Ibid.,  32,  521  (1904). 


a  minimum  was  found  with  the  following  salts:  cadmium 
iodide,  sodium  iodide,  and  hydrochloric  acid  in  mixtures  of 
ethyl  alcohol  and  water.  That  of  cadmium  iodide  exists 
for  dilutions  up  to  50  only,  at  o°;  beyond  that  there  is  no 
minimum.  At  25°  there  is  no  minimum. 

Somewhat  surprising  results  were  found  with  hydrochloric 
acid  in  methyl  alcohol  and  water  mixtures;  /*oo  occurs  at 
very  low  dilutions  in  mixtures  containing  up  to  90  per  cent, 
alcohol  (between  V  100  and  V  200),  while  in  100  per  cent. 
methyl  alcohol  it  is  not  found  even  as  high  as  V  2104.  In  the 
dilutions  above  these  limiting  values  there  is  a  decrease  in 
conductivity. 

The  relation  pointed  out  by  Wakeman, 

A 

=  constant, 


P(ioo-p) 

does  not  hold ;  neither  does  that  of  Cohen. 

They  explain  the  cause  of  the  minimum  as  follows:.  There 
are  two  factors  which  determine  conductivity,  the  amount  of 
dissociation  and  ionic  mobility.  Decrease  or  increase  of 
either  of  these  produces  a  corresponding  result  in  the  conduc- 
tivity. 

They  point  out  that  there  is  a  close  connection  between  the 
fluidity  and  conductivity  of  a  solution.  These  vary  directly. 
When  the  solutions  are  brought  together  there  is  an  increase 
in  viscosity,  or  decrease  in  fluidity,  which  is  its  reciprocal. 
Consequently,  the  ions  are  much  retarded  in  their  movements 
and  the  conductivity  diminished.  As  the  temperature  rises 
there  is  a  shifting  of  the  minima  towards  that  mixture  con- 
taining the  greatest  percentage  of  alcohol.  In  this  shifting, 
however,  the  fluidity  minima,  they  state,  lag  behind  the  con- 
ductivity minima. 

They  propose  the  following  hypothesis:  "The  conductivi- 
ties of  comparable  equivalent  solutions  of  binary  electrolytes 
in  certain  solvents  (methyl  and  ethyl  alcohol,  other  alcohols 
of  the  same  series,  acetone,  etc.)  are  inversely  proportional 
to  the  coefficients  of  viscosity  of  the  solvent  in  question,  and 
directly  proportional  to  the  association  factor  of  the  solvent 


10 

in  question."    These  conclusions  may  be  formulated  as  follows : 

—  =  constant,  or  — —  =  constant. 
x  a 

The  work  of  Jones  and  Bassett1  with  silver  nitrate  in  both 
methyl  alcohol-water  and  ethyl  alcohol-water  mixtures  deals 
with  the  same  phenomena  as  were  previously  discussed. 
There  are  well  marked  minima  in  the  curves  at  both  o°  and 
25°  in  methyl  alcohol- water  mixtures,  but  no  such  minima 
occur  in  ethyl  alcohol- water  mixtures.  In  all  cases,  however, 
the  curves  fall  much  below  the  straight  line  of  averages. 

Jones  and  Bingham2  measured  the  conductivities  of  lithium 
nitrate,  potassium  iodide,  and  calcium  nitrate  in  water,  methyl 
and  ethyl  alcohols  and  acetone,  and  binary  mixtures  of  these 
solvents.  They  also  made  a  large  number  of  viscosity  meas- 
urements of  pure  solvents,  of  mixed  solvents,  and  of  electro- 
lytes in  solution.  In  acetone  and  water  mixtures  the  same 
minima  which  previous  workers  had  observed  were  also  ob- 
served. While  the  conductivity  minima  are  intimately 
related  to  the  minima  of  fluidity,  the  conductivity  curves  of 
different  salts  show  marked  differences.  In  acetone  and  alco- 
hol mixtures  the  curves  conform  to  the  law  of  averages,  that 
is,  the  conductivity  curves  are  nearly  straight  lines.  From 
this  fact  they  conclude  that  the  mixtures  do  not  form  more 
complex  molecular  aggregations. 

A  peculiar  fact,  and  one  not  previously  known,  was  here 
discovered.  Lithium  and  calcium  nitrates  in  mixtures  of 
acetone  with  methyl  or  ethyl  alcohol  present  a  very  pronounced 
maximum  of  conduction.  This  must  be  due  to  one  of  two 
causes:  There  is  either  an  increase  in  dissociation  and,  con- 
sequently, an  increase  in  the  number  of  ions  present,  or  there 
must  be  a  diminution  in  the  size  of  the  ionic  spheres,  causing 
them  to  move  more  rapidly.  We  eliminate  the  first  cause 
since  fluidities  of  mixtures  of  acetone  and  the  alcohols  obey 
the  rule  of  averages.  This  would  indicate  that  there  is  no  in- 
crease in  the  molecular  aggregation  in  these  mixtures,  and 

1  Am.  Chem.  J.,  32,  409  (1904). 

2  Ibid.,  34,  481  (1905). 


II 

according  to  Dutoit  and  Aston's  hypothesis  such  a  mixture 
would  not  dissociate  to  a  greater  extent  than  the  constituent 
solvents.  Since  we  can  eliminate  increased  dissociation  as 
the  cause  of  the  maximum,  it  must  be  due  to  the  change  in 
the  dimensions  of  the  ionic  spheres.  The  previous  work  of 
Dutoit  and  Friederich  and  of  Jones  and  Carroll  is  incomplete 
since  it  does  not  take  into  consideration  the  size  of  the  ionic 
spheres. 

The  tendency  to  show  maxima  in  conductivity  increases 
from  potassium  iodide  through  calcium  nitrate  to  lithium  ni- 
trate, which  seem  to  show  these  effects  most  strongly.  This 
may  be  connected  with  the  ionic  velocities,  since  potassium 
is  a  small  ion  and  a  comparatively  rapidly  moving  one,  and 
lithium  forms,  by  combination  with  the  solvent,  a  large  ion 
and  one  that  moves  more  slowly. 

Jones  and  Rouiller1  worked  with  silver  nitrate  in  the  sol- 
vents used  by  Jones  and  Bingham.  In  a  general  way  they 
found  results  similar  to  those  previously  obtained.  There 
is  a  striking  similarity  in  the  curves  at  o°  and  25°  in  mixtures 
of  ethyl  alcohol  and  acetone.  There  is  a  pronounced  max- 
imum at  both  o°  and  25°  in  the  25  per  cent,  acetone  mixture 
in  the  more  concentrated  solutions,  and  shifting  with  increase 
in  dilution  through  the  50  per  cent,  mixture  to  the  75  per  cent, 
mixture.  For  pure  acetone  these  curves  decline  rapidly. 
For  mixtures  of  methyl  and  ethyl  alcohols,  the  curves  are 
nearly  straight  lines  following  the  fluidity  curves. 

Jones  and  McMaster2  worked  with  lithium  bromide  and  cobalt 
chloride  in  the  same  solvents  that  had  been  employed  by 
Bingham.  The  fluidities  of  water,  methyl  alcohol,  ethyl 
alcohol,  and  acetone,  and  binary  mixtures  of  these  solvents 
were  measured.  The  conductivities  of  these  mixtures  with 
water  show  a  well-marked  minimum.  This  minimum  shows 
an  intimate  relation  to  that  of  fluidity.  Lithium  bromide  in 
mixtures  of  methyl  and  ethyl  alcohols  gives  no  minimum  in 
conductivity.  The  curves  are  nearly  straight  lines,  except 
at  the  higher  concentrations  where  there  is  a  slight  sagging 

1  Am.  Chem.  J.,  36,  42  (1906). 

2  Ibid.,  36,325  (1906). 


12 

at  both  temperatures.  The  same  salt  shows  a  maximum  in 
conductivity  in  acetone-methyl  alcohol  mixtures  with  75 
per  cent,  acetone.  The  maxima  increase  with  rise  in  tem- 
perature. In  acetone-ethyl  alcohol  mixtures  the  same  charac- 
teristics are  manifested. 

Cobalt  chloride  in  methyl  alcohol-water  mixtures  shows 
minima  at  both  temperatures.  At  the  higher  temperature 
the  minimum  is  most  marked  with  75  per  cent,  alcohol.  In 
mixtures  of  ethyl  alcohol  and  water,  this  salt  shows  a  point  of 
inflection  at  both  temperatures  and  at  all  dilutions.  These 
results  are  similar  to  those  obtained  by  Jones  and  Bingham 
with  calcium  nitrate  in  acetone-water  mixtures.  In  ethyl 
alcohol-methyl  alcohol  mixtures  there  is  no  distinct  minimum 
but  a  sagging  of  the  curve. 

The  minimum  of  fluidity  corresponds  to  that  of  conduc- 
tivity. There  is  in  both  methyl  alcohol-water  and  ethyl  alco- 
hol-water mixtures  a  tendency  of  the  minimum  to  shift  towards 
the  mixture  containing  the  greatest  percentage  of  alcohol 
whenever  there  is  a  rise  in  temperature.  The  authors 
reach  the  conclusion  suggested  by  former  workers  that  a 
diminution  in  the  fluidity  of  the  solvent,  which  would  bring 
about  a  corresponding  decrease  in  ionic  mobility,  is  an  im- 
portant factor  in  causing  the  minimum  in  conductivity;  and 
that  the  change  in  the  size  of  the  ionic  spheres  or  the  atmos- 
phere which  surrounds  the  ions  should  also  be  taken  into 
account. 

Several  points  in  connection  with  the  temperature  coeffi- 
cients are  important.  In  nearly  every  case  the  temperature 
coefficients  are  smaller  in  the  more  concentrated  solutions. 
Jones  had  already  explained  the  phenomena  in  the  following 
manner:  In  practically  all  solutions  there  is  combination 
between  solvent  and  solute.  As  dilution  increases  the  sol- 
vates  become  more  complex.  Change  in  temperature  affects 
most  greatly  the  complex  solvates,  therefore  we  should  ex- 
pect the  largest  temperature  coefficients  at  high  dilutions. 

At  certain  concentrations  in  methyl  alcohol  and  acetone 
a  negative  temperature  coefficient  manifests  itself.  Conduc- 
tivity varies  directly  as  dissociation  and  fluidity.  Since  rise 


13 

in  temperature  diminishes  dissociation,  and  increases  fluidity, 
it  would  seem  that  there  would  be  a  point  where  these  two 
influences  would  equalize  each  other,  and  the  temperature 
coefficient  become  zero.  This  concentration  is  reached  at 
V  200  in  a  75  per  cent,  acetone  and  methyl  alcohol  mixture. 
Beyond  this  dilution  there  is  a  negative  temperature  coeffi- 
cient. 

Jones  and  Veazey1  measured  the  conductivities  and  vis- 
cosities of  solutions  of  copper  chloride  and  potassium  sulpho- 
cyanate  in  water,  methyl  alcohol,  ethyl  alcohol  and  acetone, 
and  binary  mixtures  of  thes,e  solvents.  The  minimum  which 
was  previously  observed  with  different  electrolytes  is  here 
also  observed  in  some  cases.  This  minimum  is  more  pro- 
nounced at  the  higher  dilutions.  Where  no  minimum  oc- 
curs there  is  a  decided  fall  below  the  average  value  for  the  pure 
solvents.  There  is  an  interesting  difference  in  the  values  for 
molecular  conductivity  in  the  pure  solvent  with  increasing 
dilutions.  In  pure  water,  copper  chloride,  a  ternary  electrolyte, 
shows  a  much  greater  conductivity  than  potassium  sulpho- 
cyanate,  a  binary  electrolyte.  In  pure  methyl  alcohol  the 
opposite  condition  exists.  The  conductivity  of  potassium 
sulphocyanate  is  the  greater.  This  fact  appears  in  previous 
work.  Ethyl  alcohol  shows  the  same  phenomenon. 

The  temperature  coefficients  of  conductivity  increase  with 
increase  in  dilution.  There  is  one  exception — cobalt  chloride 
in  methyl  alcohol.  A  marked  negative  temperature  coeffi- 
cient of  viscosity  is  shown  by  potassium  sulphocyanate  in 
aqueous  solutions. 

In  a  recent  communication  Jones  and  Veazey2  report  the 
results  of  a  study  of  solutions  of  tetraethylammonium  iodide 
in  mixtures  of  water,  the  alcohols  and  nitrobenzene.  In  mix- 
tures of  the  alcohols  and  water  there  is  a  well-defined  minimum 
in  conductivity.  In  mixtures  of  the  alcohols  with  each  other 
there  is  no  minimum,  although  the  curves  fall  below  the  aver- 
ages. In  methyl  alcohol  and  nitrobenzene  the  same  phe- 
nomena occur,  but  in  ethyl  alcohol  and  nitrobenzene  there  is 

1  Am.  Chem.  J.,  37,  405  (1907).  Z.  physik.  Chem.,  61,  41  (1908). 

2  Am.  Chem.  J.,  41,  433  (1909). 


14 

a  maximum.  The  conductivity  curves  correspond  very  well 
with  the  fluidity  curves. 

Jones  and  Mahin1  took  up  the  study  of  cadmium'  iodide 
and  lithium  nitrate  in  binary  mixtures  of  water,  methyl  and 
ethyl  alcohols  and  acetone,  and  lithium  nitrate  hi  ternary 
mixtures  of  these  solvents.  Viscosity  measurements  of 
these  solutions  were  also  made.  These  measurements  were 
carried  to  as  high  dilutions  as  possible — in  some  cases  as  high 
as  200,000  liters.  At  these  high  dilutions  it  was  impossible 
to  prevent  considerable  error  due  to  the  large  correction  for 
the  specific  conductivities  of  the  solvents,  and  the  large  cell 
constants.  With  lithium  nitrate  the  product  of  viscosity  and 
molecular  conductivity  is  nearly  a  constant  for  mixtures 
of  acetone  with  methyl  alcohol  and  ethyl  alcohol.  This  value 
is  independent  of  the  temperature.  The  value  is  nearly  o .  70, 
which  is  Walden's  value  for  tetraethylammonium  iodide. 
With  acetone-water  mixtures  the  product  varies  between 
i.oo,  the  value  for  water,  and  0.63,  the  value  for  acetone. 

Interesting  results  were  obtained  by  determining  the  molec- 
ular weights  of  lithium  nitrate  in  acetone  by  the  boiling-point 
method.  The  object  was  to  test  the  assumption  that  the  low 
conductivity  of  this  salt  in  ordinary  solutions  is  due  to  the 
association  of  the  salt.  In  the  most  dilute  solution — 0.09 
normal — which  could  be  determined  accurately,  the  boiling- 
point  method  showed  a  molecular  weight  of  83.1,  while  the 
normal  molecular  weight  is  69.07.  We  can,  therefore,  con- 
clude that  there  is  association,  and  this  would  account  for  the 
low  conductivity  in  solutions  at  great  dilutions. 

Jones  had  already  shown  that  cadmium  iodide  in  acetone 
is  associated.  This  salt  was  next  investigated  and  found  to 
behave  like  lithium  nitrate  in  its  molecular  conductivity. 
There  is  an  irregularity  in  the  product  of  conductivity  and 
viscosity  in  acetone  and  methyl  alcohol  mixtures,  while  in 
the  pure  solvents  these  products  are  nearly  the  same.  In 
acetone-ethyl  alcohol  mixtures  there  is  a  fair  degree  of  con- 
stancy in  these  products.  Jones  has  shown  that  there  is 
considerable  polymerization  of  cadmium  iodide  in  acetone. 

1  Z.  physik.  Chem.,  62,  41  (1908). 


15 

Conductivity  and  viscosity  in  ternary  mixtures  of  the  above 
solvents  were  next  taken  up,  and  a  considerable  amount  of 
work  was  done.  The  object  was  to  determine  whether  any 
essentially  new  pricinples  could  be  discovered  by  increasing 
the  number  of  components  in  the  solvent  mixture.  The  re- 
sults are  about  what  we  would  expect  from  a  knowledge  of 
the  behavior  of  solutions  in  binary  solvent  mixtures. 

Turner,1  working  in  Jones's  laboratory,  made  various  con- 
ductivity measurements  of  potassium  iodide,  lithium  chloride 
and  lithium  bromide  in  pure  ethyl  alcohol,  at  high  dilutions. 
Many  precautions  were  pointed  out  which  were  very  helpful 
in  the  present  work.  The  purification  of  solvents,  precau- 
tions necessary  to  prevent  contact  with  foreign  substances, 
and  other  sources  of  error  were  investigated  and  discussed  in 
detail.  After  repeated  experiments  it  was  found  that  small 
traces  (0.2  to  0.3  per  cent.)  of  water  do  not  appreciably  affect 
the  conductivity. 

The  conductivity  of  potassium  iodide  in  ethyl  alcohol  was 
measured  up  to  a  dilution  of  450,000  liters.  A  maximum  of 
molecular  conductivity  of  48.5  was  reached  at  about  20,000 
liters.  From  this  the  ionization  was  calculated.  Measure- 
ments of  conductivity  were  made  at  as  high  as  78°.  The  tem- 
perature coefficients  increase  with  increasing  temperatures 
and  with  increasing  dilution.  Ionization  decreases  consid- 
erably with  rise  in  temperature.  A  o .  i  normal  solution  is 
dissociated  49  per  cent,  at  o°,  46  per  cent,  at  25°  and  about 
35  per  cent,  at  the  boiling  point  of  ethyl  alcohol. 

Determinations  of  ionization  were  also  made  by  the  boiling- 
point  method,  but  these  are  in  all  cases  considerably  lower 
than  those  obtained  by  the  conductivity  method. 

The  work  of  Jones  and  Schmidt'8  introduces  a  new  solvent, 
glycerol.  They  measured  the  conductivity  and  viscosity  of 
lithium  bromide,  cobalt  chloride,  and  potassium  iodide  in 
glycerol,  methyl  and  ethyl  alcohols,  and  binary  mixtures  of 
these  and  water.  Glycerol  was  employed  as  a  solvent  be- 
cause of  its  high  viscosity.  Its  dielectric  constant  is  about 

1  Am.  Chem.  J.,  40,  558  (1908). 

2  Ibid.,  42,  37  (1909). 


i6 

one-fifth  that  of  water  and  it  ought  to  have  a  fairly  high  dis- 
sociating power.  It  has  remarkable  solvent  properties.  But 
little  work  had  previously  been  done  with  glycerol  as  a  sol- 
vent. For  measuring  viscosity  a  viscometer  with  especially 
large  bore  had  to  be  constructed. 

Measurements  of  conductivity  were  made  at  25°,  35°  and 
45°.  Lithium  bromide  in  mixtures  of  glycerol  with  water, 
methyl  alcohol,  and  ethyl  alcohol  shows  no  minimum,  but 
there  is  a  wide  departure  from  the  law  of  averages,  and  a 
marked  sagging  in  the  curves.  We  would  hardly  expect  a 
minimum  since  there  is  probably  no  mixture  of  glycerol  with 
these  other  solvents  which  is  more  viscous  than  glycerol  itself. 

With  cobalt  chloride  the  conductivities  in  pure  glycerol 
increase  regularly.  The  conductivity  values  are  considerably 
higher  than  the  corresponding  values  for  lithium  bromide. 
Since  cobalt  chloride  is  a  ternary  electrolyte  and  lithium 
bromide  a  binary  one,  these  results  are  just  what  we  should 
expect.  In  pure  ethyl  alcohol,  however,  the  case  is  different. 
The  values  for  the  conductivity  of  cobalt  chloride  are  ab- 
normally low.  Lithium  bromide,  for  instance,  in  a  o .  i  N 
solution  has  a  molecular  conductivity  of  15.8  at  .25°.  We 
should  expect  that  cobalt  chloride,  since  it  is  a  ternary  elec- 
trolyte, would  have  a  conductivity  probably  50  per  cent, 
greater,  but  the  value  for  the  molecular  conductivity  of  cobalt 
chloride  in  ethyl  alcohol  at  the  above  concentration  is  only 
4.71.  Many  of  the  halides  of  the  heavy  metals  tend  to  form 
complexes  when  dissolved  in  organic  solvents.  It  was  sup- 
posed that  the  low  conductivity  of  cobalt  chloride  in  ethyl 
alcohol,  at  least  in  the  more  concentrated  solutions,  was  due 
to  polymerization  of  the  molecules.  Molecular  weight  deter- 
minations of  cobalt  chloride  in  ethyl  alcohol  were  made  by 
the  boiling-point  method.  The  mean  of  three  determina- 
tions is  140  at  about  one-twelfth  normal  concentration,  while 
the  molecular  weight  for  the  compound  CoCl2  is  129.9.  This 
would  seem  to  indicate  that  there  is  association  and,  conse- 
quently, a  lower  conductivity  than  would  be  expected. 

Potassium  iodide  in  glycerol  behaves  like  the  other  salts. 
There  is  a  slight  increase  in  conductivity  with  dilution.  In 


each  case  the  conductivities  for  mixed  solvents  are  less  than 
the  average  for  pure  solvents. 

A  new  feature  is  the  magnitude  of  the  temperature  coeffi- 
cients of  conductivity.  Some  are  almost  as  high  as  nine  per 
cent.  Cobalt  chloride  in  ethyl  alcohol  manifests  a  negative 
temperature  coefficient.  A  negative  viscosity  manifests  itself 
in  the  case  of  potassium  iodide  in  water,  and  in  25  per  cent, 
and  50  per  cent,  glycerol  and  water  at  both  25°  and  35°. 

An  elaborate  investigation  has  been  carried  out  in  this 
laboratory  during  the  past  year  by  Guy  on  glycerol  as  a  sol- 
vent. The  results  of  this  work  will  soon  be  published. 

EXPERIMENTAL. 

This  investigation  was  undertaken  for  the  purpose  of  ob- 
taining facts  by  means  of  which  the  following  questions  might 
be  answered : 

1.  At  what  dilutions  do  the  maxima  in  conductivity  occur 
for  various  salts  in  methyl  and  ethyl  alcohols? 

2.  Is  there  any  relation  between  these  maxima  in  conduc- 
tivity for  different  salts  in  different  solvents? 

3.  What  is  the  magnitude  of  the  dissociation  of  these  salts 
in  these  solvents  as  calculated  by  means  of  the  maxima  in 
conductivity? 

4.  What  relation  does  this  dissociation  bear  to  that  found 
by  means  of  the  boiling-point  method? 

Apparatus. 

The  Kohlrausch  method  was  used.  The  wire  was  calibra- 
ted and  was  found  to  be  of  uniform  thickness  throughout. 

The  cells  were  of  the  latest  type  used  in  this  laboratory. 
They  were  devised  for  measuring  the  conductivity  of  very 
dilute  solutions  where  there  is  great  resistance.  They  con- 
sist of  two  concentric  platinum  cylinders  so  placed  one  within 
the  other  that  the  electrodes  are  only  about  i  mm.  apart.  They 
are  held  together  by  means  of  small  drops  of  fusion  glass 
placed  between  them.  These  electrodes  have  a  surface  of 
about  48.75  square  cm.  One  of  these  cells  had  a  constant 
as  low  as  2.82.  The  vertical  position  of  the  electrodes  per- 


i8 

mitted  the  ready  escape  of  all  air  bubbles,  neither  were  they 
difficult  to  wash  and  dry  if  the  proper  precautions  were  ob- 
served. These  cells  gave  excellent  results,  and  a  sharp  min- 
imum was  obtained  upon  the  bridge  without  difficulty.  The 
constants  were  determined  by  means  of  o.oi  N  and  o.ooi  N 
solutions  of  potassium  chloride.  These  constants  were  fre- 
quently redetermined  but  were  found  to  change  but  little 
throughout  the  work. 

All  the  appparatus  was  carefully  calibrated.  The  necessary 
precautions  concerning  temperature  were  observed.  The 
temperature  in  the  25°  bath  was  regulated  with  a  sensitive 


•ez^ 

^ 

J 

f^--± 

Fig.  I. — Type  of  cell  employed  in  this  work. 

thermometer  calibrated  against  a  German  Reichanstalt  ther- 
mometer. The  o°  bath  was  from  time  to  time  tested  to  see 
that  there  was  no  change  in  temperature.  At  no  time  were 
measurements  made  when  the  temperature  varied  more  than 
o°.04  from  that  required.  Careful  tests  were  made  to  find 
the  time  required  for  the  temperature  of  the  solutions  within 
the  cells,  both  at  o°  and  25°,  to  reach  an  equilibrium.  This 
equilibrium  was  indicated  by  a  constant  conductivity.  In 
all  cases  nearly  an  hour  was  necessary.  Three  readings  were 
always  taken  and  the  mean  was  employed. 

For  o°  measurements  a  battery  jar  filled  with  ice  and  water 
was  placed  within  a  bucket  and  surrounded  with  ice  and 
water.  The  cells  were  placed  in  the  battery  jar  and  covered 


19 

with  glass.  Ample  time  was  allowed  for  the  temperature 
to  reach  an  equilibrium.  Frequently  the  first  reading  was 
repeated  after  an  interval  of  fifteen  minutes  or  more,  insuring 
equilibrium. 

Extreme  precautions  were  necessary  in  washing  the  ap- 
paratus. No  fumes  were  permitted  in  the  room.  Immediately 
before  using,  the  cells  and  flasks  were  thoroughly  washed  with 
distilled  water,  then  rinsed  several  times  with  conductivity 
water  and  finally  washed  repeatedly  with  alcohol.  This  alco- 
hol was  always  kept  pure  and  used  only  a  few  times  before  it 
was  dried  and  redistilled.  Ether  was  not  employed  in  drying 
since  there  is  danger  of  fats  being  contained  in  it.  The  ap- 
paratus was  then  carefully  dried.  Before  a  solution  was 
made  up  in  a  flask  the  latter  was  rinsed  with  a  portion  of  the 
solvent,  and  the  cell  was  rinsed  with  a  portion  of  the  solution. 
In  many  cases  of  very  dilute  solutions  the  flask  in  which  the 
solution  was  to  be  made  up  was  first  cleaned,  dried  and  rinsed 
with  alcohol,  the  conductivity  of  this  alcohol  determined, 
and  this  same  alcohol  was  employed  to  dilute  the  solution 
and  its  conductivity  was  used  for  the  correction  for  the 
specific  conductivity  of  the  solvent.  As  a  rule,  there  was  lit- 
tle change  in  this  conductivity  when  the  above  precautions 
were  observed,  and  yet,  because  of  the  large  volume,  this 
change  was  at  times  quite  appreciable. 

Salts. 

The  salts  used  were  potassium  iodide,  ammonium  bromide, 
potassium  sulphocyanate,  lithium  nitrate,  sodium  iodide, 
copper  chloride,  calcium  nitrate  and  cobalt  chloride. 

In  all  cases  the  necessary  precautions  were  observed  in 
purifying  the  salts,  Kahlbaum's  best  products  being  employed. 
All  were  recrystallized  a  number  ,of  times,  finally  from  con- 
ductivity water  and  some  from  absolute  alcohol.  All  were 
dried  at  a  temperature  of  125°- 150°.  Those  which  are  very 
deliquescent  were  heated  for  a  long  time,  some  for  several 
days,  in  ah  air  bath.  Those  chlorides  which  readily  form 
oxychlorides  when  heated  in  the  air  were  recrystallized  several 
times,  then  dried  in  a  vacuum  desiccator  over  sulphuric  acid 


20 

for  several  days,  and  finally  heated  for  a  long  time  in  a  cur- 
rent of  dry  hydrochloric  acid  gas.  They  were  then  placed  in 
a  desiccator  over  sulphuric  acid  and  potassium  hydroxide  for 
several  days.  All  other  salts  but  the  latter  class  were  dried 
to  constant  weight  before  making  up  each  solution. 

Solvents. 

The  solvents  used  were  methyl  and  ethyl  alcohols  and  mix- 
tures of  these  with  water.  Considerable  difficulty  was  ex- 
perienced in  purifying  methyl  alcohol  so  as  to  obtain  it  with 
as  low  a  specific  conductivity  as  possible.  This  low  conduc- 
tivity was  important  since  there  was  danger  of  introducing 
considerable  error  due  to  the  large  correction  for  the  specific 
conductivity  of  the  solvent  at  these  high  dilutions.  It  was 
evident  from  the  results  that  some  foreign  substance  was  con- 
tained in  the  methyl  alcohol  which  it  was  difficult  to  remove. 
It  was  supposed  that  this  unusually  high  conductivity  was 
due  probably  to  pyridine  bases,  and  that  these  might  be  re- 
moved by  treatment  with  sulphuric  acid.  The  cold  alcohol 
was  treated  with  a  small  quantity  of  dilute  sulphuric  acid. 
It  was  then  distilled,  the  first  runnings  being  always  discarded, 
and  the  receiver  removed  while  a  considerable  quantity  was 
still  in  the  flask.  The  alcohol  was  then  boiled  with  lime  for  a 
day  and  distilled.  In  some  cases  it  was  repeatedly  treated 
with  lime  and  repeatedly  distilled.  One  quantity  thus  treated 
gave  a  conductivity  as  low  as  7.  i  X  io~7.  On  standing,  how- 
ever, the  conductivity  changed  somewhat,  so  that  not  all 
work  was  done  with  alcohol  having  quite  such  low  conduc- 
tivity. 

The  ethyl  alcohol  was  distilled  from  lime  several  times, 
then  repeatedly  distilled  until  it  had  a  conductivity  of  about 
2.6  X  io~7.  The  water  was  purified  by  the  method  of  Jones 
and  Mackay. 

Solutions. 

All  solutions  were  made  by  direct  weighing.  In  those  cases 
where  the  solutions  were  to  be  very  dilute  and  but  a  small 
quantity  of  the  salt  was  needed,  a  o .  i  N  solution  was  made  as  a 
mother  solution.  This  was  then  diluted  to  a  second  mother 


21 

solution.  From  this  the  final  dilutions  were  made  directly. 
Only  in  a  few  cases  was  a  final  dilution  made  from  any  other 
but  the  first  or  the  second  mother  solution. 

All  solutions  were  made  up  at  20°.  Enough  time  was  al- 
ways allowed  for  the  temperature  to  come  to  equilibrium. 
The  solutions  when  once  placed  in  the  cells  were  not  removed 
from  them  until  after  measurements  were  made  for  both 
temperatures.  They  were  never  left  in  the  cells  longer  than 
necessary  because  of  possible  decomposition : 

Table  I. — Conductivity  of  Potassium  Iodide  in  Methyl  Alcohol 
ato°  and  2*>°. 


V. 

0°. 

25°. 

Temperature 
coefficients. 

1024 

69.05 

96.18 

0.01572 

2048 

70.62 

99.22 

O.OI62O 

4096 

71.48 

101.  14 

0.01660 

8192 

72.13 

102.4 

0.01679 

16384 

74-5 

104.8 

0.01627 

32768 

76.6 

107.2 

0.01598 

Table  II. — Conductivity  of  Potassium  Iodide  in  Ethyl  Alcohol 

ato°  and  25°. 

Temperature 
V.  0°.  25°.  coefficients. 

1024         23.4          36.4          0.02222 

2048  28.6  44-9  0.02280 

4096  29.4  47 -2  0.02422 

8192  32.7  47.5  0.01810 

16584  32.5  47.4  0.01834 

33168  32.0  47.2  0.01900 

Table   III. — Conductivity   of   Ammonium   Bromide   in   Methyl 
Alcohol  at  o°  and  25°. 

Temperature 
V.  0°.  25°.  coefficients. 

1024      66.1       93.1       0.01634 

2048  69.9  94.1  0.01377 

4096  70.6  96.7"  0.01482 

8129  71.8  96.8  0.01393 

16584  69.2  94.9  0.01485 


22 


Table    IV. — Conductivity    of    Ammonium    Bromide    in    Ethyl 
Alcohol  at  o°  and  25°. 


V. 

0°. 

25°. 

Temperature 
coefficients. 

1024 

32.1 

37-0 

O.O2O47 

4096 

25.2 

39-6 

0.02285 

16384 

27-5 

39-i 

0.01687 

65536 

29.8 

39-5 

O.OI3O2 

Table  V. — Conductivity  of  Potassium  Sulphocyanate  in  Methyl 
Alcohol  at  o°  and  25°. 

Temperature 
V.  0°.  25°.  coefficients. 


1600 

69.1 

98.3 

0.01690 

3200 

71.1 

101  .0 

0.01682 

12800 

73-o 

103.7 

0.01682 

25600 

83.5 

106.3 

0.01092 

Table  VI. — Conductivity  of  Potassium  Sulphocyanate  in  Ethyl 
Alcohol  at  o°  and  2$( 


V. 

0°. 

25°. 

Temperature 
coefficients. 

1600 

28.2 

43-8 

0.02218 

3200 

28.6 

45-7 

0.02391 

6400 

29.2 

46.67 

0.02393 

12800 

29.23 

45-4 

0.02213 

25600 

28.57 

43-64 

0.02  I  10 

Table  VII. — Conductivity  of  Lithium  Nitrate  in  Methyl  Alco- 
hol at  o°  and  25°. 


Temperature 

V. 

0°. 

25°. 

coefficients. 

1600 

58.83 

83.24 

0.01659 

3200 

59-89 

85.98 

0.01743 

6400 

61  .46 

89.29 

O.OlSlI 

12800 

59-69 

91-35 

0.02  12  I 

25600 

60.36 

93.61 

O.O22O3 

Table  VIII. — Conductivity  of  Lithium  Nitrate  in  Ethyl  Alcohol 
at  o°  and  25°. 

Temperature 
V.  0°.  25°.  coefficients. 


1600 

23.82 

36.67 

0.02157 

3200 

24.13 

38.44 

0.02372 

6400 

25-63 

40.87 

0.02378 

12800 

25.87 

40.02 

0.02187 

25600 

43-30 

0  .  OOOOO 

Table  IX. — Conductivity  of  Sodium  Iodide  in  Methyl 
at  o°  and  25' 


V. 

0°. 

25°. 

Temperature 
coefficients. 

512 

60.32 

87.67 

O.Ol8l4 

1024 

64.15 

90.91 

0.01669 

2048 

63-65 

91-93 

0.01777 

4096 

63-34 

91  .06 

0.02382 

8192 

65.90 

93-40 

0.01669 

16384 

63.1 

91.8 

O.Ol8l9 

Table  X.  —  Conductivity  of  Sodium  Iodide  in 

Ethyl  Alcohol  at 

0° 

and  25°. 

Temperature 

V. 

0°. 

25°. 

coefficients. 

512 

24.41 

38.06 

0.02237 

1024 

25.12 

39-66 

0.02315 

2048 

25.89 

40.92 

O.O2322 

4096 

26.89 

41.84 

0.02224 

8192 

26.06 

42.86 

0.02579 

16384 

26.79 

42.02 

O.O2274 

32768 

28.8-3 

43.22 

O.OI996 

Table  XL  —  Conductivity  of 

Calcium  Nitrate 

in  Methyl  Alco- 

hoi  at 

o°  and  25°. 

Temperature 

V. 

0°. 

25°. 

coefficients. 

1600 

83.53 

IO6.O4 

O.OIO78 

3200 

93-50 

120.58 

O.OII56 

6400 

105.46 

138.46 

O.OI252 

12800 

112.52 

I5L73 

0.01394 

25600 

119.44 

164.6 

O.OI509 

51200 

124-58 

175.0 

O.OI620 

Table  XII.  —  Conductivity  of 

Calcium  Nitrate 

in  Ethyl  Alcohol 

at  o 

0  and  25°. 

Temperature 

v. 

0°. 

25°. 

coefficients. 

1600 

17.19 

24.48 

0.01696 

3200 

19.  ii 

29.52 

O.O2I79 

6400 

21-45 

34.16 

0.02370 

12800 

24.22 

39-23 

0.02537 

25600 

27.61 

45.67 

O.O26l6 

51200 

31.92 

51.62 

0.02469 

24 

Table  XIII. — Conductivity  of  Cobalt  Chloride  in  Methyl  Alcohol 


ato° 

and  25°. 

Temperature 

V. 

o*. 

25°. 

coefficients. 

1600 

101  .94 

138.58 

O.OI438 

3200 

110.98 

152.34 

0.01878 

6400 

115.76 

162.38 

o.  01612 

12800 

116.22 

165-74 

0.01704 

25600 

ii5-34 

166.08 

0.01760 

51200 

112.58 

I57-96 

9.01614 

Table  XIV  —Conductivity  of 

Cobalt  Chloride  1 

in  Ethyl  Alcohol 

ato° 

and  25°. 

Temperature 

V. 

0°. 

25°. 

coefficients. 

1600 

19.99 

25.61 

O.OII25 

3200 

22.75 

30.13 

0.01298 

6400 

25.68 

34-15 

O.OI3I9 

12800 

29.25 

39-Qi 

0.01335 

25600 

3I-36 

43.62 

0.01564 

51200 

31.62 

46.31 

0.01858 

102400 

28.42 

(52.26) 

0  .  00000 

Table  XV.—  ( 

Conductivity  of  Copper  Chloride  in  Methyl  Alco- 

hol at  o 

0  and  25°. 

Temperature 

V. 

0°. 

25°. 

coefficients. 

1600 

64-13 

78.58 

0.09013 

3200 

75-43 

89-31 

0.07361 

6400 

85.22 

101.28 

0.07538 

12800 

91-3 

112.3 

0.09201 

25600 

90.5 

116.4 

O.OII45 

51200 

79.1 

112.  I 

0.01669 

Table  XV  I.  —Conductivity  of 

Copper  Chloride 

in  Ethyl  Alco- 

hoi  ato°  and  25°. 

Temperature 

V. 

0°. 

25°. 

coefficients. 

1600 

16.08 

20.96 

O.OI2I4 

3200 

18.94 

25-74 

0.01436 

6400 

21  .06 

30.70 

O.OI83I 

12800 

22.52 

34.16 

O.O2067 

25600 

22.94 

37-79 

0.02589 

25 

Table  XVII. — Conductivity  of  Potassium  Iodide  in  a  Mixture 
of  25  Per  Cent.  Methyl  Alcohol  and  Water. 


Temperature 

V. 

0°. 

25°. 

coefficients. 

1024 

45-03 

90.44 

0.04023 

2048 

44.26 

91.60 

0.04278 

4096 

45.60 

92.80 

0.04140 

8192 

45-56 

92.40 

0.04II2 

16384 

48.60 

96.0 

o  .  04000 

32768 

51-99 

100-7 

0.04517 

Table  XVIII. — Conductivity  of  Potassium  Iodide  in  a  Mixture 
of  50  Per  Cent.  Ethyl  Alcohol  and  Water. 


V. 

0°. 

25°. 

Temperature 
coefficients. 

1024 

35-77 

72.24 

0.04078 

2048 

36.07 

73-37 

0.04137 

4096 

37-49 

74.64 

0.03968 

8192 

38.04 

76.20 

0.04013 

16384 

40.18 

79-9 

0.03945 

36768 

46.86 

93-i 

0.03948 

Table  XIX. — Conductivity  of  Potassium  Iodide  in  a  Mixture 
of  75  Per  Cent.  Methyl  Alcohol  and  Water. 


V. 

0°. 

25°. 

Temperature 
coefficients. 

1024 

41-63 

71-37 

0.04952 

2048 

41  .20 

72.00 

o  .  05064 

4096 

41.82 

73-19 

0.05247 

8192 

44.98 

75-41 

0-05475 

16384 

46.83 

75-3 

0.05339 

32768 

49-95 

71.8 

O.OI9IO 

Table  XX. — Conductivity  of  Potassium  Iodide  in  a  Mixture  of 
25  Per  Cent.  Ethyl  Alcohol  and  Water. 

Temperature 


V. 

0°. 

25°. 

coefficients. 

1024 

32.38 

74-80 

0.05241 

2048 

32.75 

76.23 

0.053II 

4096 

32.73 

76.60 

0.05361 

8192 

33-88 

77.20 

0.05II5 

16584 

35-30 

80.3 

0.05138 

33168 

39-88 

86.8 

o  .  04702 

26 

Table  XXL— -Conductivity  of  Potassium  Iodide  in   a   Mixture 
of  50  Per  Cent.  Ethyl  Alcohol  and  Water. 

Temperature 


V. 

0°. 

25°. 

coefficients. 

1024 

20.04 

52.12 

0.06401 

2048 

20.92 

52.83 

O.O6O73 

4096 

21.28 

53-20 

o  .  06000 

8192 

21.34 

54-09 

0.06120 

16384 

20.94 

55-23 

0.06550 

32768 

23.10 

59-i6 

0.06244 

Table  XXII. — Conductivity  of  Potassium  Iodide  in  a  Mixture 
°f  75  Per  Cent.  Ethyl  Alcohol  and  Water. 


Temperature 

V. 

0°. 

25°. 

coefficients. 

1024 

20.58 

44.14 

0.04579 

2048 

21-39 

45-04 

0.04423 

4096 

21.50 

45-91 

0.04541 

8192 

21.34 

45-96 

0.04615 

16384 

21.85 

47-85 

0.04760 

32768 

23-68 

51.04 

0.04491 

65536 

25.11 

53-30 

0.04491 

Table  XXIII.  —  Conductivity  of  Cobalt  Chloride  in  a  Mixture 
of  25  Per  Cent.  Methyl  Alcohol  and  Water. 


Temperature 


V. 

0°. 

25°. 

coefficients. 

i6oo 

66.85 

I44.I 

0.04620 

3200 

68.20 

148.5 

0.04831 

6400 

69-39 

I5I.8 

0.04749 

12800 

70.50 

152.3 

0.04641 

25600 

72.08 

159-0 

0.04823 

51200 

80.30 

181.6 

o  .  05046 

Table  XXIV. — Conductivity  of  Cobalt  Chloride  in  a  Mixture  of 
50  Per  Cent.  Methyl  Alcohol  and  Water. 


V. 

0°. 

25°. 

Temperature 
coefficients. 

1600 

53-94 

II3-5 

0.04417 

3200 

55-84 

II5-7 

0.04287 

6400 

56.59 

IIQ.4 

o  .  04440 

12800 

57.86 

122.3 

0.04456 

25600 

58.70 

124.  I 

0.04457 

51200 

65.2 

138.6 

0.04503 

27 

Table  XXV. — Conductivity  of  Cobalt  Chloride  in  a  Mixture  of 
75  Per  Cent.  Methyl  Alcohol  and  Water. 


V.                              0°. 

Temperature 
25°.                        coefficients. 

1600             56.23 

IOI-5                     O.O322O 

3200             63.32 

II5.4                     0.03290 

6400              64.22 

118.1               0.03356 

12800                66.48 

120-7                     O.O3262 

25600               66.2 

122.3                     0.93390 

51200               69.0 

124.9                     0.63241 

Table  XXVI.  —  Conductivity  of  Cobalt  Chloride  in  a  Mixture 

of  25  Per  Cent.  Ethyl 

Alcohol  and  Water. 

Temperature 

V.                             0°. 

25  °.                        coefficients. 

1600               47  .  92 

II9.7                     0.05992 

3200               49.  08 

123.6                     0.06072 

6400               50  .  80 

127.4                     O.O6032 

12800               50.73 

129.7                     O.O6227 

25600               51-83 

135.0                     0.06419 

51200               57-74 

154.4                     0.06697 

162400               60.20 

170.5                     0.07327 

Table  XXVII  —Conductivity  of 

Cobalt  Chloride  in  a  Mixture 

of  50  Per  Cent.  Ethyl 

Alcohol  and  Water. 

Temperature 

V.                              0°. 

25  °.                       coefficients. 

1600               31.16 

81.56                     0.06469 

3200               32.27 

84.67                     0.06495 

6400               32  .  70 

86.56                     0.06588 

12800               33-70 

88.28                     0.06479 

25600               33.25 

87.42                     0.06517 

51200               34  -^ 

90.8                        0.07743 

102400               34-40 

89.7                        O.07609 

Table  XXV  1  1  1.  —Conductivity  of 

Cobalt  Chloride  in  a  Mixture 

of  75  Per  Cent.  Ethyl 

Alcohol  and  Water. 

Temperature 

V.                            0°. 

25°.                         coefficients. 

1600                31.0 

67.1                        0.04658 

3200                32.4 

70.5                        0.04704 

6400               33  .  i 

73.4                        0.04870 

12800               33.7 

74.6                        0.04855 

25600               34.4 

74.8                        0.04698 

51200               34.0 

72.4                        0.04518 

28 

Table  XXIX. — Conductivity  of  Potassium  Iodide  in  Mixtures 
of  Methyl  Alcohol  and  Water  at  o°. 


V. 

0  per  cent. 

25  per  cent. 

50  per  cent. 

75  per  cent. 

100  per  cen 

1024 

87.9 

45.0* 

35-8 

41.6* 

69.  I 

2048 

88.5 

44-3 

36.1 

41.2 

70.6* 

4096 

88.9 

45-6 

37-5 

41.8 

71-5 

8192 

89.2* 

46.6 

38.0* 

45-o 

72.1 

16384 

89.2 

46.6 

40.2 

46.8 

74-5 

32768 

89.2 

52.0 

46.9 

49-9 

76.6 

Table  XXX. — Conductivity  of  Potassium  Iodide  in  Mixtures  of 
Methyl  Alcohol  and  Water  at  25°. 


V. 

0  per  cent.    25  per  cent.  50  per  cent. 

75  per  cent. 

100  per  o 

1024 

135-6 

90.4 

72.2 

71.4 

96.2 

2048 

136.2 

91.6 

73.4 

72.0 

99-2 

4096 

136.7 

92.8* 

74.7 

73-2 

IOI.I 

8192 

136.9* 

92.4 

76.2 

75-4* 

IO2.4 

16584 

136.9 

95-3 

79-9 

75-3 

104.8 

33168 

136.9 

100.7 

93-i 

71.8 

107.2 

Table  XXXI. — Conductivity  of  Potassium  Iodide  in  Mixtures 
of  Ethyl  Alcohol  and  Water  at  o°. 

nt.    100  per  cent. 

23-4 
28.6 
29.4 

32.7* 

32.5 
32.0 


Table  XXXII. — Conductivity  of  Potassium  Iodide  in  Mixtures 
of  Ethyl  Alcohol  and  Water  at  25°. 

V.  0  per  cent.    25  per  cent.    50  per  cent.    75  per  cent.     100  per  cent. 


F. 

0  per  cent. 

25  per  cent. 

50  per  cent.   75  per  ce 

1024 

87- 

9 

32.4 

20 

.O 

20. 

6 

2048 

88. 

5 

32.8* 

20 

9 

21  . 

4 

4096 

88. 

9 

32.7 

21 

3* 

21  . 

5 

8192 

89. 

2* 

33-9 

21 

3 

21  . 

3 

16584 

89. 

2 

35-3 

20 

9 

21  . 

8 

33168 

89. 

2 

39-9 

23 

,i 

23- 

7 

65536 

25- 

i 

IO24 

135.6 

74.1 

52-1 

44.1 

36.4 

2048 

136.2 

76.2 

52-8 

45-0 

44.9 

4096 

136.7* 

76.6 

53-2 

45-9 

47.2 

8192 

136.9 

77.2 

54.  i 

46.0* 

47-5 

16584 

136.9 

80.3 

55-2 

47-9 

47-4* 

33l68 

136.9 

86.8 

59-2 

51-0 

47-2 

29 

Table  XXXIII —Conductivity  of  Cobalt  Chloride  in  Mixtures 
of  Methyl  Alcohol  and  Water  at  o°. 


V. 

25  per  cent. 

50  per  cent. 

75  per  cent. 

100  per  cen 

1600 

66.9 

53-9 

56.2 

101  .9 

3200 

68.2 

55-8 

63.3 

III  .0 

6400 

69.4 

56.6 

64.2 

II5.8 

12800 

75-5* 

57-9 

66.5* 

116.2* 

25600 

72.1 

58.7 

66.2 

115.3 

51200 

80.3 

65-2 

69.0 

112  .6 

Table  XXXIV. — Conductivity  of  Cobalt  Chloride  in  Mixtures 


v. 


of  Methyl  Alcohol  and  Water  at  25°. 

25  per  cent.        50  per  cent.       75  per  cent.         100  per  cent. 


1600 

144.1 

II3-5 

101.5 

138.58 

3200 

148.5 

II5-7 

II5-4 

152.34 

6400 

151.8 

119.4 

118.1 

162.38 

12800 

152.3 

122.3 

120.7 

165.74 

25600 

159-0 

124.  i 

122.3 

166.1 

51200 

181.6 

136.6 

124.9 

158.0 

Table  XXXV. — Conductivity  of  Cobalt  Chloride  in  Mixtures  of 
Ethyl  Alcohol  and  Water  at  o°. 


v. 


25  per  cent.   50  per  cent.   75  per  cent.    100  per  cent. 


1600 

47.92 

31.16 

31.0 

19.99 

3200 

49.08 

32.27 

32.4 

22.75 

6400 

50.80* 

32.70 

33-i 

25-68 

12800 

50.73 

33  •  70* 

33.7 

29.25 

25600 

51.83 

33.25 

34-4* 

31-36 

51200 

57.74 

34-i8 

34-o 

31.62* 

162400 

60.20 

34-40 

28.42 

Table  XXXVI.— Conductivity  of  Cobalt  Chloride  in  Mixtures 
of  Ethyl  Alcohol  and  Water  at  25°. 


V. 

25  per  cent. 

50  per  cent. 

75  per  cent. 

100  per  cent. 

1600 

II9.7 

81.56 

67.I 

25.61 

3200 

123.6 

84.67 

70.5 

30.13 

6400 

127.4 

86.56 

73.4 

34.15 

12800 

129.7 

88.28 

74  6 

39-01 

25600 

135-0 

87.42 

74.8 

43.62 

51200 

154-4 

90.8 

72.4 

46.31 

30 

Table  XXXVII. — Dissociation  of  Potassium  Iodide  in  Mix- 
tures of  Methyl  Alcohol  and  Water  at  o°. 

V.  0  per  cent.     25  per  cent.     50  per  cent.     75  per  cent.    100  per  cent. 

1024  98.4  ioo.  o  94.2  ioo.  o          97.8 

2048  99.2  ...  95.0  ...           100.0 

4096  100.0  ...  98.7 

8192              ...  ...  100.0 


Table  XXXVIII. — Dissociation  of  Potassium  Iodide  in  Mix- 
tures of  Ethyl  Alcohol  and  Water  at  o°. 

V.  0  per  cent.     25  per  cent.     50  per  cent.     75  per  cent.     100  per  cent. 

1024  98.4  98.7  93.9  95.8  71.5 

2048  99.2         100.0  98.1  99.5  &7-4 

4096  loo.o         loo.o         100.0         100.0          90.0 

8192  ...  ...  ...  ...  100.0 


Table  XXXIX. — Dissociation  of  Cobalt  Chloride  in  Mixtures 
of  Methyl  Alcohol  and  Water  at  o°. 

V.  0  per  cent.       25  per  cent.     50  per  cent.     75  per  cent.    100  per  cent. 

1600           100.0           88.6           ...             84.5  87.6 

3200              ..'.             90.3            ...             95-i  95-5 

6400                               91.9                             96.5  99.6 

12800                             100.0                          100.0  100.0 


Table  XL. — Dissociation  of  Cobalt  Chloride  in    Mixtures    of 
Ethyl  Alcohol  and  Water  at  o°. 

V.               0  per  cent.      25  per  cent.     50  per  cent.     75  per  cent.  100  per  cent. 

1600     100.0    94.2     92.5    93.0  63.2 

3200        ...        96.6       95.7       94.1  72.0 

6400      ...     100.0     97.0     96.2  8  i.  2 

12800     ;••,  ;    •••     100.0    97.9  92.5 

25600      ,.*      ...      ...     100.0  92.2 

5I2OO        v.  .        ...        ...        ...  IOO.O 


Table  XLI. — Maxima  in  Molecular  Conductivity  for  Certain 
Salts  in  Pure  Alcohols. 

0°.  25°. 

KI  in  methyl  alcohol                 (77-5)  (112.6) 

KI  in  ethyl  alcohol                      32.7  47 . 5 

NH4Br  in  methyl  alcohol            71.8  96 . 8 

NH4Br  in  ethyl  alcohol              (30. 3)  39.6 

KCNS  in  methyl  alcohol           (69 . 2)  (110.4) 

KCNS  in  ethyl  alcohol                29.2  46 . 7 

LiNOg  in  methyl  alcohol            61.5  (96 . 7) 

IyiNO3  in  ethyl  alcohol                25.9  40 . 8 

Nal  in  methyl  alcohol                64.  i  91 .9 

Nal  in  ethyl  alcohol                    27.0  42.8 

CuCl2  in  methyl  alcohol              91.3  116.4 

CuCl2  in  ethyl  alcohol                (25.7)  (32.7) 

Ca(NO3)2  in  methyl  alcohol        

Ca(NO3)2  in  ethyl  alcohol  

CoCl2  in  methyl  alcohol            116.2  166 .  o 

CoCl2  in  ethyl"  alcohol                  31.6  (46 . 7) 


Table 

Solvent. 

53 • 949 

55-352 
61.195 
52.842 
57.480 
55.686 
54-510 
59-798 

55 • 546 

53-215 


Boiling-Point  Data. 
XLI  I. — Sodium  Iodide  in  Methyl  Alcohol. 

Concen- 
tration. 

0.03478 
0.03300 
O.O279O 
0.02661 
0.02560 
0.02108 
O.O2268 

o . 02005 

O.OI42I 
O.OI2II 


Salt. 
2.8I3I 

2-7357 

2-5597 

2 . 1082 
2 . 2O6O 
1.7227 
1.8380 
I. 8080 

I • 1943 
0.9665 


Rise. 
0.429 

0-425 

0.3556 

0-347 

0.318 

0.263 

0.298 

0.251 

0.178 

0.155 


Molecular 
rise. 

12-33 
12.90 
12.74 
13.04 
12.42 
12.50 

I3-I4 
12.52 
12.52 


12.  80 


Dissocia- 
tion. 

46.8 
53-6 
51-8 

55-2 
47-8 
48.8 
56.4 
49-o 
49-o 
52-4 


Solvent. 

53 • I0° 
54-734 
64.744 

53-896 
61.293 

55-509 
61 .701 

59-294 
54-368 
64.926 


Table  XLIII. 

Salt. 

3-I7I5 
2.7683 

3 . 2084 
2.6133 
2.5117 
2.0431 

2.1323 
i . 9686 
1-5300 
1.4171 


-Sodium 

Concen- 
tration. 

0.03984 
0.03374 
0.03303 
0.03235 
0.02730 
0.02455 
O.O23O6 
O.O22I4 
0.01877 
0.01455 


Iodide  in  Ethyl  Alcohol. 

Molecular 
rise. 

14.63 


Rise. 

0.585 
0.512 

0-495 
0.481 
0.402 
0-365 
o.35i 
0.327 
0.281 
0.223 


Dissocia- 
tion. 


14.98 
14.87 

14-73 
14.86 
15.22 
14.76 
14.97 
I5-32 


27.7 

31-9 
30.2 

29-3 
28.0 
29.1 

32-3 
28.3 
30.1 

33-2 


32 
Table  XLIV. — Calcium  Nitrate  in  Methyl  Alcohol. 


Concen- 

Molecular 

Dissocia- 

Solvent. 

Salt. 

tration. 

Rise. 

rise. 

tion. 

56  .  762 

1-4954 

O.OI685 

o.  160 

9.969 

9-5 

64.823 

1.2154 

O.OII42 

0.107 

9.366 

8.6 

52.567 

0.9792 

O.OII35 

o.  106 

9-340 

6.8 

63-825 

1.2489 

O.OII3I 

O.IIO 

9-725 

7.9 

62.275 

0-7453 

O.OO729 

0.073 

IO.OO9 

9-3 

Table  XLV  .—Calcium  Nitrate  in  Ethyl  Alcohol. 


Solvent. 
50.476 
54-301 
52.355 

Salt. 
I  .  IOO4 
1-3570 
0.6795 

Concen- 
tration. 

O.OI328 
0.01228 
O.O079I 

Rise. 

12.68 
12.86 
12.51 

Molecular 
rise. 

0.168 
1.158 
0.099 

Dissocia- 
tion. 

5-i 
5-9 
4-4 

Table  XLVI. — Cadmium  Iodide  in  Ethyl  Alcohol. 

Concen-  Molecular     Dissocia- 


Solvent. 

Salt. 

tration. 

Rise. 

rise. 

tion. 

48.831 

3-59I5 

0.02007 

0.253 

12.  60 

4.8 

54-657 

3.6962 

0.01850 

0.230 

12-43 

4-05 

50.956 

3.1632 

0.01694 

0.214 

12.63 

4-9 

51-574 

2.9277 

0.01549 

0.195 

12.58 

4-7 

52.348 

2.7683 

0.01443 

0.181 

12-57 

4-6 

52.316 

2.6784 

0.01397 

o.  176 

12.58 

4-6 

48.034 

2.U37 

O.OI2OI 

0.152 

12.67 

5-o 

51.668 

I.249I 

o  .  00660 

0.082 

12  .42 

4.0 

56  •  563 

O.87I2 

o  .  04204 

0.052 

12.38 

4-3 

DISCUSSION   OF   RESULTS. 

Tables  I  to  XVI  show  the  conductivity  of  the  various  salts 
worked  with  in  the  pure  solvents  at  both  o°  and  25°.  Nine 
of  these  tables  show  a  maximum  either  at  one  or  both  tem- 
peratures. The  other  tables  show  no  maximum  up  to  the 
highest  dilutions  measured.  In  several  cases  maxima  occur 
at  one  temperature  and  none  at  the  other.  In  some  tables 
the  maxima  occur  at  the  same  concentration  at  both  tem- 
peratures ;  in  others  at  different  concentrations,  but  they  always 
occur  at  concentrations  which  are  close  together.  The  tem- 


33 

perature  coefficients  in  general  agree  very  well.  Nearly  all 
show  a  slight  increase  with  increasing  dilution. 

Tables  XVII  to  XXVIII  show  the  conductivity  of  potas- 
sium iodide  and  cobalt  chloride  in  mixtures  of  methyl  alcohol 
and  water  at  both  o°  and  25°.  In  some  of  these  tables  the 
maximum  conductivities  are  reached.  The  maxima  generally 
occur  at  a  greater  concentration  at  o°  than  at  25°.  In  a  few 
tables  the  maxima  occur  at  the  same  concentration  at  both 
temperatures.  In  nearly  every  case  where  there  is  a  maximum 
there  is  a  slight  decrease  in  conductivity,  then  a  rapid  increase 
as  dilution  increases,  thus  giving  an  inflection  in  the  curve. 

Figs.  II  to  IV  give  the  curves  for  the  conductivities  of  potas- 


o  25  50  75  xoo 

Fig.  II. — Conductivity  of  potassium  iodide  in  mixtures  of  methyl  alcohol  and  water 

atO°. 


34 

slum  iodide  in  mixtures  of  methyl  alcohol  and  water  and  of 
ethyl  alcohol  and  water.  The  abscissas  represent  the  per- 
centage of  alcohol  and  the  ordinates  represent  the  conductiv- 


140 


130 


no 


100 


80 


70 


o  25  50  75  100 

Fig.  III. — Conductivity  of  potassium  iodide  in  mixtures  of  methyl  alcohol  and  water 

at  25°. 

ity.  In  Fig.  II  there  is  a  marked  minimum  with  50  per  cent, 
methyl  alcohol.  Fig.  Ill  shows  a  minimum  with  75  per  cent, 
methyl  alcohol.  Fig.  IV  for  potassium  iodide  in  methyl 
alcohol-water  mixtures  shows  the  same  characteristics.  Fig. 


35 

V  shows  a  minimum  for  only  three  concentrations ;  these  are 
with  75  per  cent,  ethyl  alcohol. 

Figs.  VI  to  IX  are  the  curves  for  the  conductivity  of  cobalt 
chloride  in  methyl  alcohol-water  mixtures  and  ethyl  alcohol- 
water  mixtures  at  both  o°  and  25  °.  Fig.  VI  shows  a  minimum 


20 


o  25  50  75  XOO 

Fig.  IV. — Conductivity  of  potassium  iodide  in  mixtures  of  ethyl  alcohol  and  water  at  0°. 

with  50  per  cent,  methyl  alcohol.  Fig.  VII  shows  minima 
in  the  curves  with  75  per  cent,  methyl  alcohol.  In  Figs. 
VIII  and  IX  there  is  no  minimum. 


Tables  XIXX  to  XXXVI  represent  the  values  for  the  con- 
ductivities of  potassium  iodide  and  cobalt  chloride  in  mixed 
solvents,  arranged  according  to  temperature.  The  propor- 


100 


70 


60 


40 


o  25  so  75  ioo 

Fig.  V. — Conductivity  of  potassium  iodide  in  mixtures  of  ethyl  alcohol  and  water  at  25  °. 

tions  in  which  the  solvents  are  mixed  and  the  concentrations 
vary.  A  study  of  the  maxima  of  conductivity  in  these  tables 
is  interesting.  The  more  probable  values  for  /*  <»  are  indicated 
by  a  (*).  By  means  of  these  values  I  have  calculated  the  dis- 


37 

sociation  of  the  salts  at  different  volumes  for  four  of  these  tables 
(XXIX,  XXXI,  XXXIII,  and  XXXV) ,  since  these  present  more 
/£  oo values  than  the  rest.  I  have  used  the  well-known  equa- 


o  25  50  75  100 

Fig.  VI. — Conductivity  of  cobalt  chloride  in  mixtures  of  methyl  alcohol  and  water  at  0°. 


tion,  a  =  —  and  the  values  for  a  are  given  in  Tables  XXXVII 

to  XL.      In  Table  XXXIII   no  /ceo  occurs  for  50  per  cent, 
methyl  alcohol- water  mixtures. 

These  values  for   dissociation  are  interesting  when  com- 
pared with  the  values  for  the  corresponding  molecular  conduc- 


38 

tivities.  Fig.  X  gives  the  curves  for  dissociation  corresponding 
to  the  molecular  conductivity  as  indicated  by  the  curves  in 
Fig.  IV.  Fig.  XI  in  the  same  manner  corresponds  to  Fig.  VI 
and  Fig.  XII  to  Fig.  VIII. 


100 


o  25  so  7  100 

Fig.  VII. — Conductivity  of  cobalt  chloride  in  mixtures  of  methyl    alcohol  and  water 

at  25°. 

In  Fig.  IV  the  conductivity  curves  of  potassium  iodide  in 
ethyl  alcohol- water  mixtures  at  o°  show  minima  for  all  dilu- 
tions, while  the  corresponding  curves  for  dissociation  in  Fig. 

X  at  first  rise.     If  the    equation  a  =  —  holds  for  mixed  sol- 


39 


vents  this  would  indicate  that  at  o°  the  dissociation  in  25 
per  cent,  ethyl  alcohol-water  mixtures  is  slightly  greater  than 
in  pure  water.  In  all  mixtures  the  dissociation  is  very  much 
greater  than  it  is  in  pure  alcohol. 


10 


o  25  50  75  ioo 

Fig.  VIII. — Conductivity  of  cobalt  chloride  in  mixtures  of  ethyl  alcohol  and   water 

at  0°. 

Fig.  XI  gives  the  curves  for  cobalt  chloride  in  methyl  alco- 
hol-water mixtures  corresponding  to  the  molecular  conduc- 
tivity as  represented  by  Fig.  VI.  The  curves  for  dissocia- 


40 

tionr  show  minima,  but  the  drop  below  the  straight  line  of 
averages  is  very  small  when  compared  with  the  large  and 
decided  minima  in  Fig.  VI. 


160 


140 


80- 


40 


o  25  50  75  100 

Fig.  IX. — Conductivity  of  cobalt  chloride  in  mixtures  of  ethyl  alcohol  and  water  at  25  *. 

Fig.  XII  for  dissociation  corresponds  to  Fig.  VIII  for  molec- 
ular conductivity.  The  relation  between  these  two  figures 
is  similar  to  the  relation  between  X  and  IX.  In  both  cases 
the  mixed  solvents  are  ethyl  alcohol  and  water.  In  this  case 


we  have  a  binary  salt,  and  the  curves  for  Figs.  X  and  XII  are 
strikingly  similar. 


o  as  So  75  zoo 

Pig.  X. — Dissociation  of  potassium  iodide  in  mixtures  of  ethyl  alcohol  and  water  at  0*. 

The  curves  representing  dissociation  in  ethyl  alcohol-water 
mixtures  are  sometimes  upward  curves,  taking  a  direction  oppo- 


110 


00 


80 


I  I  I 

o  25  50  75  too 

Fig.  XI. — Dissociation  of  cobalt  chloride  in  mixtures  of  methyl  alcohol  and  water  at  0*. 

site  to  that  of  the  curves  representing  conductivity,  which  are 
downward  curves.  This  fact  is  especially  apparent  when  Fig.  IV, 


42 

giving  the  curves  for  the  conductivity  of  potassium  iodide 
in  mixtures  of  ethyl  alcohol  and  water  at  o°,  is  compared 
with  Fig.  X,  which  gives  the  curves  for  the  dissociation  of  these 
same  solutions.  This  plainly  indicates  that  the  greatly  dimin- 
ished conductivity  in  mixed  solvents  is  due  not  to  diminished 
dissociation  but  to  the  other  factor  conditioning  conductivity, 
viz.,  diminished  velocity  of  the  ions  through  the  solution. 
Though  it  had  been  previously  pointed  out  that  this  diminished 


80 


60 


o  25  50  75  ioo 

Fig.  XII. — Dissociation  of  cobalt  chloride  in  mixtures  of  ethyl  alcohol  and  water  at  0°. 

conductivity  is  due  almost  entirely  to  increased  viscosity  of  the 
mixed  solvent,  it  was  not  definitely  known  what  the  magnitude 
of  the  dissociation  in  these  mixed  solvents  is,  nor  was  it  sus- 
pected that  this  dissociation  might  be  greater  in  the  mixed 
than  in  the  pure  solvents,  as  is  shown  to  be  the  case  by  the 
curves  for  dissociation,  some  of  these  curves  having  maxima 
while  those  of  conductivity  have  decided  minima.  These  facts 
are  quite  marked  where  ethyl  alcohol-water  mixtures  are  used 


43 

as  solvents.  In  such  cases  the  increased  viscosity,  on  the  one 
hand,  diminishes  the  conductivity,  and  the  decreased  dissocia- 
tion, on  the  other,  increases  the  conductivity.  The  viscosity 
in  this  case,  since  it  is  the  more  potent  factor,  causes  the  large 
minima  in  the  curves  for  conductivity.  These  minima  would 
be  more  marked  than  they  are  were  it  not  for  the  slightly 
increased  dissociation. 

Table  XU  gives  the  /*«>  values  of  molecular  conduc- 
tivity for  the  various  salts  studied  both  in  methyl  and  in  ethyl 
alcohols  at  o°  and  at  25°,  whenever  such  values  could  be 
found.  The  values  without  the  brackets  were  determined 
experimentally.  Those  within  the  brackets  could  not  be 
determined  experimentally  because  of  the  great  dilutions 
and  consequently  unavoidable  errors,  but  were  calculated  by  a 
method  given  below. 

An  examination  of  the  table  reveals  the  fact  that  there  is 
some  relation  between  the  maximum  for  each  salt  in  the  differ- 
ent solvents  at  any  given  temperature.  It  was  suspected 
that  this  relation  is  a  constant  and  that  the  following  equa- 
tion would  hold  : 

^oo  methyl 

—  constant. 


,. 
J"  oo  ethyl 

This  equation  was  then  applied  with  the  following  results: 
Binary  Electrolytes. 

LiNO3at    o°  =2.37. 

Nal  o°  =  2.37. 

NH4Br      25°  =2.44. 

Nal  25°  =2.17. 

Ternary  Electrolytes. 
CoCl2ato°    =3.68. 

These  facts  make  it  appear  probable  that  there  is  approxi- 
mately such  a  constant  for  binary  electrolytes  and  another  for 
ternary  electrolytes.  These  data  are  not  sufficient,  however, 
to  give  a  final  value  to  such  constants.  Further  investigations 
will  be  required  for  this  purpose.  Most  of  these  maxima  occur 


44 

at  dilutions  of  V  =  12,800  to  V  =  51,200.  At  these  dilutions 
it  is  very  difficult  to  obtain  accurate  results  and  the  values 
for  the  constant  are  probably  within  the  limits  of  experimen- 
tal error. 

The  value  for  the  constant  between  methyl  and  ethyl  alcohols 
for  binary  electrolytes  appears  to  be  very  nearly  2 .37.  I  have 
obtained  but  one  value  for  ternary  electrolytes,  which  is 
3.68.  That  is  nearly  1.5  X  2.37.  The  latter  value  (3.56) 
is  probably  the  more  nearly  correct.  The  factor  i .  5  is  em- 
ployed -since  this  expresses  the  ratio  of  ions  present  between 
binary  and  ternary  electrolytes  at  complete  dissociation. 

With  the  data  in  hand  I  proceeded  to  test  further  the 
accuracy  of  the  above  equation  by  supplying  by  calculation 
in  Table  XU  those  //«  values  which  could  not  be  deter- 
mined experimentally.  The  value  of  the  constant  was  taken  as 
2.37  for  binary  electrolytes  and  3,56  for  ternary  electrolytes. 
The  calculated  value  for  potassium  iodide  in  methyl  alcohol 
at  o°  from  the  value  in  ethyl  alcohol  would  be  77.5.  An  ex- 
amination of  Table  I  reveals  the  fact  that  this  value  is  proba- 
bly very  nearly  correct.  For  25°  it  would  be  112.6.  Again 
from  the  same  table  this  is  probably  correct.  Ammonium  bro- 
mide in  ethyl  alcohol  at  o°  would  be  equal  to  30. 3.  This  too 
as  indicated  by  Table  IV  is  probably  nearly  correct.  Potassium 
sulphocyanate  in  methyl  alcohol  at  25  °  would  have  a  value  of 
110.4.  Table  V  indicates  that  this  value  is  probably  correct 
within  the  limits  of  experimental  error.  Lithium  nitrate  gives 
a  value  of  96.7  in  methyl  alcohol  at  25°;  compared  with 
Table  VII  this  would  seem  to  be  nearly  correct. 

With  ternary  electrolytes  there  are  only  three  cases  to  which 
this  equation  can  be  applied.  Copper  chloride  in  ethyl  alco- 
hol at  o°  would  give  a  value  of  24.8,  and  cobalt  chloride  in 
ethyl  alcohol  at  25°  would  give  46.7  as  the  value  for  the 
maximum  in  conductivity.  In  Table  XIV,  at  o°,  a  maximum 
is  reached  at  V  =  25600.  The  maxima  at  the  different  tem- 
peratures as  a  rule  do  not  occur  very  far  apart.  We  believe 
that  the  value  46 . 7  is  pretty  nearly  correct  for  the  maximum 
for  cobalt  chloride  in  ethyl  alcohol  at  25°.  The  only  two 
values  which  do  not  fit  into  the  table  are  the  value  for  potas- 


45 

slum  cyanide  in  methyl  alcohol  at  o°  and  that  for  copper 
chloride  in  ethyl  alcohol  at  25°.  The  latter,  however,  is  not 
far  from  what  we  might  expect  it  to  be. 

I  believe  from  the  above  results  that  the  ratio  between 
the  maxima  in  molecular  conductivity  for  different  salts  in 
methyl  alcohol  and  the  maxima  for  the  same  salts  in  ethyl 
alcohol  is  probably  constant  for  all  binary  electrolytes,  that  for 
all  ternary  electrolytes  it  is  a  constant  of  different  value,  and 
that  there  is  a  definite  relation  between  these  two  constants. 

Jones,  in  an  article  on  "The  Electrolytic  Dissociation  of 
Certain  Salts  in  Methyl  and  Ethyl  Alcohols,  as  Measured  by 
the  Boiling-Point  Method,"  gives  the  following  table  which 
expresses  "the  dissociation  values  of  the  above  alcohols  as 
calculated  from  data  obtained  by  the  boiling-point  method." 
The  ratios  of  these  values  were  calculated  and  are  also  ex- 
pressed in  the  table : 

Table  XLVIL 

Dissociation    Dissociation 

Ratio. 
2.08 
1.8 
2-5 
2-3 
2-3 
2.7 

3-o 

Leaving  out  the  value  1.8  for  sodium  iodide,  which  is  evi- 
dently erroneous,  we  obtain  as  a  mean  from  the  other  values 
of  the  binary  electrolytes  2.37  which,  it  will  be  remembered, 
is  the  same  as  the  value  obtained  above  by  the  conductivity 
method  for  the  ratio  between  the  maxima  in  the  different 
alcohols.  The  value  in  this  table  for  the  one  ternary  electro- 
lyte is  not  so  great  as  that  determined  by  the  conductivity 
method,  and  yet  it  is  possible  that  more  data  would  give 
comparable  values. 

The  boiling-point  data  in  this  work  were  obtained  by  means 


in  methyl 
Dilution           alcohol. 

in  ethyl 
alcohol. 

Substance. 

normal.         Per  cent. 

Per  cent. 

KI 

0. 

52 

25 

Nal 

O. 

60 

33 

NaBr 

0. 

60 

24 

NH4Br 

0. 

49 

21 

CH3COOK 

O. 

36 

16 

CH3COONa 

0. 

38 

14 

Ca(N03)2 

0. 

15 

5 

46 

of  the  boiling-point  apparatus  used  by  Jones.1     Both  solvents 
were  carefully  purified  and  dried. 

Table  XUV   gives  thelksociation  of  certain  salts  as  cal- 
culated by  both  the  conductivity  and  boiling-point  methods: 

Table 


Dissociation  from  Dissociation  from 
conductivity  boiling-point 

method.  method. 

Salt.  Solvent.  Per  cent.  Per  cent. 

KI  Methyl  65  49 

KI  Ethyl  49  26 

Nal  Methyl  75  61 

NH4Br  Methyl  71  47 

NH4Br  Ethyl  40  20 

It  will  be  seen  at  a  glance  from  the  above  table  that  the  dis- 
sociation values  as  determined  by  conductivity  are  higher 
than  those  found  by  the  boiling-point  method,  in  both  methyl 
and  ethyl  alcohols.  This  may  possibly  be  due  to  a  poly- 
merization of  the  undissociated  molecules  in  the  solvent  in 
question.  This  would  give  too  low  dissociation  as  measured 
by  the  boiling-point  method,  since  this  method  takes  into  ac- 
count both  the  molecules  and  the  ions,  while  the  conductivity 
method  deals  only  with  the  ions. 

SUMMARY. 

I  have  measured  the  conductivity  of  various  salts  in  pure 
methyl  and  ethyl  alcohols  at  very  high  dilutions,  and  also  in 
mixtures  of  methyl  and  ethyl  alcohols  with  water.  In  many 
of  these  measurements  I  have  found  the  value  of  H&. 

Many  of  these  values  were  found  to  occur  at  concentra- 
tions between  V  =  3200  and  V  =  51200. 

A  constant  ratio  was    found   between   the   values  of   //» 

for  several  binary  electrolytes  in  methyl  alcohol  and  in  ethyl 

alcohol,  and  the  ratio  for  one  ternary  electrolyte  was  worked 

out.    These  facts  indicate  that  there  is  a   definite   relation 

between  these  two  ratios. 

I  have  found  minima  in  most  of  the  curves  for  mixed 
solvents. 

I  have  tabulated  the  dissociation  of  several  salts  in  methyl 
alcohol  and  ethyl  alcohol  as  determined  by  the  boiling-point 
method. 

*  Z.  physik.  Chem..  31,  114  (1899)  (Jubelband  zu  van't  HoffV 


BIOGRAPHY 

The  author  of  this  dissertation,  Henry  Royer  Kreider,  was 
born  near  Millheim,  Pennsylvania,  April  24,  1874.  His  pre- 
paratory training  was  received  in  the  public  schools  and  in  the 
Spring  Mills  Academy.  He  entered  Franklin  and  Marshall 
College  in  1894  from  which  he  received  the  degree  of  A.B.,  in 
1898,  and  A.M.,  in  1901.  Since  then  he  has  taught  in  differ- 
ent schools  and  academies.  The  year  1904-5  was  spent  in 
graduate 'work  at  the  Johns  Hopkins  University.  After  teach- 
ing for  several  years  in  the  Pennsylvania  State-Forest  Academy 
he  again  entered  the  Johns  Hopkins  University  in  1907.  For 
several  years  since  then  a  part  of  the  time  was  devoted  to 
teaching. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
BERKELEY 


Return  to  desk  from  which  borrowed. 
This  book  is  DUE  on  the  last  date  stamped  below. 


•'* 

- 


<& 

.. 


LD  21-100m-ll,'49(B7146sl6)476 


Stockton,  Calif. 
T.  M.  Reg.  U.S.  Pat.  Off. 


THE  UNIVERSITY  OF  CALIFORNIA  UBRARY 


